The present invention relates to a load adjustment device having a control element which acts on a setting member which determines the output of an internal combustion engine, the control element cooperating with a driver which is coupled to an accelerator pedal and, in addition, being controllable by an electric setting drive which cooperates with an electronic control device.
Load adjustment devices, for instance load adjustment devices which cooperate with carburetors or injection pumps, must satisfy the requirement of optimal regulation of the internal combustion engine over the entire range of loads. For this purpose, a complicated construction or control of the corresponding load adjustment device is required. Thus carburetors, for instance, in addition to the actual means for the formation of the mixture, have additional devices such as leaning, starting, idling, accelerating and economizing devices, etc. These means complicate the construction of the carburetor and result in a high expense for structural parts, in particular, for instance, additional injection nozzles, pumps, special developments of the nozzle needles, separate air feeds are necessary, entirely aside from the high control requirements connected therewith.
It is particularly important in load adjustment devices to control the state of load upon idling, at which only minimum power is given off by the internal combustion engines. But, as compared with certain circumstances, particularly in motor vehicles, there may be load-consuming devices which require extensive power, such as fans, rear-window heating, air conditioning, etc. In order to take these possible power requirements into account, control of the load adjustment device between a maximum idle position and a minimum idle position is necessary. Upon failure of the control, an emergency idle position of the setting member or control member is to be assured.
In contradistinction to the problem described above, load adjustment devices of the type indicated are used, as a general rule, in cases where the accelerator pedal and the setting member are electronically connected to each other. The accelerator pedal is coupled with the driver and the latter is coupled with the control element. Furthermore, a desired-value detection element which is associated with the driver and an actual-value detection element which cooperates with the desired-value detection element and acts on the electric setting drive are provided. The electric setting drive is adapted to be controlled by the electronic control means as a function of the values detected. The electrical connection of accelerator pedal and setting member with the electronic control means interposed between them makes it possible to set desired-value positions predetermined by the accelerator pedal and the driver connected with it with reference to the actual values indicated by the position of the control element and of the setting member. The values are checked for the existence or absence of plausibility conditions, so that if certain plausibility conditions are present or absent, the possibility exists of acting, via the electronic means by control of the electric setting drive, on the setting member, which may be developed, for instance, as throttle valve or injection pump, in order to correct it. Thus, for instance, action by the electronic control means may be provided in order to avoid wheel slippage upon starting as a result of the giving of excessive power through the gas pedal. Other automatic interventions in the load adjustment device are, for instance, conceivable in connection with automatic shifting processes of a transmission, a speed-limiting control, or the above-mentioned idling control of the internal combustion engine.